It's longer than a football field, taller than a brontosaurus and heavier than a throng of sperm whales. The Port of Miami Tunnel Project's massive tunnel-boring machine—a $45 million earthworm of Goliath proportions—will begin carving out sister tunnels for the thriving hub this month.

The Miami Access Tunnel

The Miami Access Tunnel

Each workday, 16,000 vehicles squeeze onto a bridge to the Port of Miami on Dodge Island (upper land mass in the image). Dodge Island—between downtown Miami on the mainland and Miami Beach—is the second largest economic generator in Miami-Dade County. But because there is only one access route to the Port, the streets of downtown are often clogged with bumper-to-bumper traffic.

Relief is on the way, thanks to the work of a big machine. This month, the enormous tunnel-boring machine (TBM)—"the most advanced of its generation," according to its creators—will begin a mission to sculpt a tunnel more than 40 feet in diameter and 3900 feet long through the limestone recesses under the waters of Government Cut.

The hope is that by May 2014 the tunnel will open and eliminate the rush-hour traffic jams and early morning migraines, all without a toll. A local Girl Scout troop dubbed the machine "Harriet" in honor of Harriet Tubman, the courageous woman who led slaves to freedom through the Underground Railroad.

Launch Pit

Launch Pit

It begins here. The Port of Miami Tunnel Project crew created this 50-foot-deep concrete-lined "launch pad," which extends 400 feet up the median of the MacArthur Causeway. It's the starting point of Harriet's subterranean slog.